It can be diagnosed that late. Some of the stuff that you are describing sounds like my son, and he saw a neurologist yesterday that confirmed what we already highly suspected; that he has an autistic spectrum disorder, likely Asperger's. Since your son had no huge issues and probably had good preacademic skills, that may be why it really only seemed to be more of an issue when he hit school age. I'm not an expert by any means, but I have been doing a lot of research since we started suspecting that this was what we were looking at. In addition, the nice doctor also said that you have what is called the autistic spectrum. There are different types of autism, with varying degrees of functionality. Your son sounds very high level to me. Your pediatrician may ask you to see a neurologist or a neuropsychologist. That's about as much as I know at this point (though I plan to get very homey with this process myself). Best of luck.